Six Sigma is the most widely used strategy for statistical quality assurance in industry
today. Originally popularized by Motorola in the 1980s, the Six Sigma strategy ―is a
rigorous and disciplined methodology that uses data and statistical analysis to measure
and improve a company‘s operational performance by identifying and eliminating
defects‘ in manufacturing and service-related processes. The term Six Sigma is derived
from six standard deviations—instances (defects) per million occurrences—implying an
extremely high quality standard. The Six Sigma methodology defines three core steps:
Define customer requirements and deliverables and project goals via well-defined
methods of customer communication.
Measure the existing process and its output to determine current quality performance
(collect defect metrics).
Analyze defect metrics and determine the vital few causes.
If an existing software process is in place, but improvement is required, Six Sigma
suggests two additional steps:
Improve the process by eliminating the root causes of defects.
Control the process to ensure that future work does not reintroduce the causes of
defects.
These core and additional steps are sometimes referred to as the DMAIC (define,
measure, analyze, improve, and control) method. If an organization is developing a
software process (rather than improving an existing process), the core steps are
augmented as follows:
Define customer requirements and deliverables and project goals via well-defined
methods of customer communication.
Measure the existing process and its output to determine current quality performance
(collect defect metrics).
Analyze defect metrics and determine the vital few causes.
Design the process to (1) avoid the root causes of defects and (2) to meet customer
requirements.
Verify that the process model will, in fact, avoid defects and meet customer
requirements.
This variation is sometimes called the DMADV (define, measure, analyze, design, and
verify) method.